1. Field of the Invention
The present invention relates to a sleeve rotation-feed apparatus for feeding a thin film sleeve used in an electrophotographic process of development, transfer, and fixation in an electrophotographic copying machine and an electrophotographic printer, and to a developing apparatus, image formation apparatus, and fixation apparatus using this sleeve rotation-feed apparatus.
2. Description of the Related Art
Conventionally, this type of thin film sleeve feeding apparatus is known, for example, in an electrostatic latent image developing apparatus disclosed in Japanese Patent Publication 1-234869.
FIG. 11 shows configuration of a sleeve feeder in this electrostatic latent image developing apparatus.
This electrostatic latent image developing apparatus includes: a drive roller 110 for rotation, a cylindrical thin film member (thin film sleeve) 111 having a circumferential length slightly greater than that of the drive roller 110, a guide member 109 for pressing the thin film member 111 against the drive roller 110, a layer thickness regulating member 112 in pressed contact with the outer surface of the thin film member 111, and the like.
The guide member 109 has an arc-shaped inner surface corresponding to the outer shape of the drive roller 110. Accordingly, this guide member 109 brings the thin film member 111 into contact with the circumference of the drive roller 110, so that a sag of the thin film member 111 is concentrated to an open portion provided against a photosensitive drum 100 of the guide number 109 and a predetermined space S is formed between the drive roller 110 and the thin film member 111. Thus, toner supplied by the layer thickness regulating member 112 to the outer surface of the thin film member 111 is supplied to the outer surface of the photosensitive drum 100 for development of an electrostatic latent image.
Here, assuming .mu.1 as a friction coefficient between the outer circumference of the drive roller 110 and the inner circumference of the thin film member 111 and .mu.2 as a friction coefficient between the outer circumference of the thin film member 111 and the guide member 109, the relationship .mu.1&gt;&gt;.mu.2 is satisfied. When the drive roller 110 rotates in the direction of the arrow b, the thin film member 111 is also fed in the same direction.
Apart from the aforementioned electrostatic latent image developing apparatus, there is known a sleeve rotation-feed apparatus having the identical configuration used as a photosensitive belt feed apparatus.
That is, in this photosensitive belt feed apparatus, a thin film having a photosensitive function or the like is painted or formed by deposition on a thin film member (thin film sleeve) constituting a photosensitive belt base. A drive roller is arranged inside the loop of this photosensitive belt and a guide member is arranged outside the loop, so that the photosensitive belt is fed in the same way as the configuration shown in FIG. 11.
However, in the aforementioned conventional sleeve rotation-feed apparatus, the respective member materials should be selected so as to satisfy the relationship of friction coefficients as .mu.1&gt;&gt;.mu.2. This reduces flexibility of the design and causes a disadvantage in reducing the cost.
Moreover, since the thin film member 111 is pressed by the guide member 109 or the like against the drive roller 110, scratches may be caused on the outer circumference of the thin film member 111 which is in contact with the guide member 109.
Especially, in the aforementioned photosensitive belt in the feed apparatus, a scratch grows as the operation time increases, resulting in a short service life of the apparatus.
In order to prevent generation of such a scratch, a soft cloth piece may be used to a portion where the guide member is in contact with the thin film member. However, the effect is considered to be small.
Moreover, in the aforementioned conventional apparatus, dusts and toner come into the portion between the thin film member and the drive roller. This lowers the friction force and the sleeve rotation becomes unstable, causing a defective image. On the other hand, in order to rotate at a high speed while suppressing generation of speed irregularities, it is necessary to increase the friction force between the drive roller and the thin film member. For this, the thin film member should be pressed to the drive roller with a greater force. This makes greater the problem of scratch generation on the thin film member. In the conventional apparatus, this has been an obstacle in obtaining a high-speed rotation.
Moreover, when the friction force is increased, the drive torque of the drive roller is increased, increasing the motor size, disabling energy saving.